MBI bioaerosol vortex cassette

ABSTRACT

An insert for a cassette that is adapted to sample particulate matter in air. The insert has an upstream end that is circular and a downstream end that is flange shaped with substantially smooth walls between the upstream and downstream ends of the insert. The cassette with the insert disposed therein is also described.

[0001] The 25-millimeter (mm) cassette equipment with a 0.8-micron mixed cellulose ester (MCE) filters are routinely used in the practice of industrial hygiene. More specifically, these cassettes are commonly used in the evaluation of airborne concentrations of asbestos. Bioaerosol agents can be recovered with the standard use of these cassettes, however; problems exist with regard to analyses of data collected by standard methodologies. The MBI Bioaerosol Vortex Cassette is designed specifically for the collection and identification of airborne biological agents such as fungal spores and pollen. Typically most fungal bioaerosol components are above 1 micron in size. Hence, filters having a pore size just below 1 micron are useful in the filtration of fungal bioparticulate from the air without excessive air resistance. After collection, filters can be prepared for culture and/or viewed microscopically. Filtration technologies vastly improve recovery efficiency. In the past, direct filter examination has proven impractical because of the time required to collect samples, desiccation of recovered spores, as well as, increased man-hour and equipment costs. However, the MBI Bioaerosol Vortex Cassette represents a new design that concentrates fungal bioparticulate into a distinct zone on the receiving filter. The concentration of recovered agents in effect reduces the collection area of the MCE filter thus allowing a reduction in sampling time without compromising detection levels or filter integrity. The MBI Bioaerosol Vortex Cassette capitalizes on standard and accepted sampling methodologies, but now expands the use of 0.8 micron MCE filtration collection methodology into the field of fungal and other bioaerosol identification and reporting.

BACKGROUND OF THE INVENTION

[0002] Air sampling is used to quantify and qualify the contents of an environment. Laboratory analyses of the samples provide critical information relative to the potential exposure to harmful agents. Bioaerosol sampling focuses these processes on particles of biological origin. These agents include, but are not limited to, viable and non-viable fungal spores, bacteria, pollen, skin cells, fibers and insect parts.

[0003] The 25-millimeter (mm) cassette equipment with a 0.8-micron mixed cellulose ester (MCE) filters are routinely used in the practice of industrial hygiene. More specifically, these cassettes are commonly used in the evaluation of airborne concentrations of asbestos. Bioaerosol agents can be recovered with the standard use of these cassettes, however; problems exist with regard to analyses of data collected by standard methodologies. Bioaerosol components are usually in far less airborne concentrations when compared to asbestos related industrial hygiene and/or abatement projects. Therefore, it becomes necessary to sample greater volumes of air in order to achieve appropriate detectable levels of bioaerosols using MCE filter technology. Airflow turbulence occur if 0.8-micron mixed cellulose ester filters are exposed to air velocities over 15 liters per minute (L/m) that result in non-uniform particle distribution. Therefore, the rate of airflow cannot be adjusted over 15 L/m without potential damage to the MCE filter. Therefore, sample time is the only parameter available for manipulation. Under normal conditions, several hours of sampling are required in order to obtained an appropriate volume of air for bioaerosol analyses. These time constraints are problematic, especially when considering the costs related to on-site technical man-hours and/or the need for additional equipment for each individual sample location. The MBI Bioaerosol Vortex Cassette has the unique ability to reduce sampling time to minutes without damaging MCE filters and thereby creating a highly efficient and effective bioaerosols recovery unit.

BRIEF SUMMARY OF INVENTION

[0004] The MBI Bioaerosol Vortex Cassette is designed for a specific niche in the marketplace. Until recently, bioaerosol sampling has been performed using two basic types of collection methodologies; filtration and impact. Filtration methodologies utilize filter cassettes that are equipped with filters having a variety of design, components, and pore sizes. Typically most fungal bioaerosol components are above 1 micron in size. Hence, filters having a pore size just below 1 micron are useful in the filtration of fungal bioparticulate from the air without excessive air resistance. After collection, filters can be prepared for culture and/or viewed microscopically. The use of filters for fungal culture has proven to be inefficient with regard to recovery and is typically not recommended. Direct observation under microscope is possible, however; typically the sampling time required to collect detectable amounts rendered this sampling technique as implausible. Impacting methods have emerged as the principle means to evaluate airborne fungal bioparticulate. Impacting occurs directly onto agar-media surfaces for culture or on to special fixatives for direct microscopic examination. While some benefits exist with respect to culture recovery, the overall processes inherently introduces a bias of recovery and generally requires at least 5-7 days for incubation prior to analyses. Impacting directly on to special fixatives does allow the potential for an immediate analysis, however; some limits exist with regard to identification and classification.

[0005] Regardless, impaction methods remain vulnerable to a variety of parameters that effect “recovery efficiency”. These factors include airflow, particle size, aerodynamics, etc. . . . No impacting sampler is 100% efficient. Therefore, some percentage bioparticulate merely passes through the sampler and remains undetected.

[0006] Filtration technologies vastly improve recovery efficiency. The selection of filter pore sizes that are below the dimensions of fungal particulate ensures retention. Culture from filters have demonstrate relatively low recovery and are not generally recommended for air sampling, however; direct microscopic examination of filters offers an improved recovery efficiency over traditional impacting methods. In the past, direct filter examination has proven impractical because of the time required to collect samples, desiccation of recovered spores, as well as, increased man-hour and equipment costs. However, the MBI Bioaerosol Vortex Cassette represents a new design that concentrates fungal bioparticulate into a distinct zone on the receiving filter. The concentration of recovered agents in effect reduces the collection area of the MCE filter thus allowing a reduction in sampling time without compromising detection levels or filter integrity. The MBI Bioaerosol Vortex Cassette capitalizes on standard and accepted sampling methodologies, but now expands the use of 0.8 micron MCE filtration collection methodology into the field of fungal and other bioaerosol identification and reporting.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007]FIG. 1 depicts a standard 25-millimeter (mm) cassette containing the MBI Bioaerosol Vortex Cassette.

[0008]FIG. 2 is an exploded front and side view of the 25-millimeter (mm) cassette containing the MBI Bioaerosol Vortex Cassette.

[0009]FIG. 3 are side front and side views of the MBI Bioaerosol Vortex Cassette with general dimensions.

DETAILED DESCRIPTION OF THE DRAWINGS

[0010]FIG. 1 depicts a standard 25-millimeter (mm) cassette containing the MBI Bioaerosol Vortex Cassette. The barrel (C) is wholly adaptable to existing designs and technologies utilizing 25-mm cassettes. Reference A identifies the in-port tubing cap. The tubing cap can be removed to allow the linking with tubing for remote collections in generally inaccessible spaces such as interstitial walls, crawl spaces, attics, etc. . . . Reference B identifies the intake cap. The intake cap (B) is removed prior to the collection air and/or surface samples. The MBI Bioaerosol Vortex Cassette barrel (C) is attached to the filter canister (D). The filter canister contains a retention layer (G) supporting a 0.8-micron MCE filter (F) (not visible in this illustration). Reference E identifies the out-port tubing cap. The out-port tubing cap is removed to allow the attachment of a suction tube from a vacuum pump having a flow rate capacity between one (1) and fifteen (15) liters per minute. Operation of the vacuum pump draws air into the cassette. The MBI Bioaerosol Vortex Cassette collects, funnels, concentrates, and deposit particulate onto the 0.8 micron MCE filter contained in the filter canister.

[0011]FIG. 2 is an exploded front and side view of the 25-millimeter (mm) cassette containing the MBI Bioaerosol Vortex Cassette. The insert is wholly adaptable to existing designs and technologies utilizing 25-mm cassettes. Reference A identifies the in-port tubing cap. The tubing cap can be removed to allow the linking with tubing for remote collections in generally inaccessible spaces such as interstitial walls, crawl spaces, attics, etc. . . . Reference B identifies the intake cap. The intake cap (B) is removed prior to the collection air and/or surface samples. The MBI Bioaerosol Vortex Cassette barrel (C) is attached to the filter canister (D). The filter canister contains a retention layer (G) supporting a 0.8-micron MCE filter (F). Reference E identifies the out-port tubing cap. The out-port tubing cap is removed to allow the attachment of a suction tube from a vacuum pump having a flow rate capacity between one (1) and fifteen (15) liters per minute. Operation of the vacuum pump draws air into the cassette. The MBI Bioaerosol Vortex Cassette collects, funnels, concentrates, and deposit particulate onto the 0.8 micron MCE filter contained in the filter canister.

[0012]FIG. 3 are front and side views of the MBI Bioaerosol Vortex Cassette with general dimensions. The opening of the MBI Bioaerosol Vortex Cassette barrel has an upper diameter of 29.0 millimeters (mm). The upper 16-mm has two distinct beveled layers capable of attaching to standard a 25 mm intake cap. The upper layer is approximately 7.5 mm in length. Total length of the barrel is approximately 50.0 mm. The internal barrel has a design length of approximately 46.0 mm which will terminate approximately 1-2 mm from the surface of the 0.8-micron MCE filter contained in the filter canister. However, the mechanism will be design such that the insert can actual touch the surface of the filter to enhance collection recovery under certain conditions. The insert begins as a circular structure that transitions into a vortex that narrows from top to bottom. The illustration indicates the bottom opening has outer diameter of between 5 and 15.0 mm and generally designed to create a filter deposition trace having a diameter of 5 and 15 mm. However, these dimensions will vary in production, thus allowing the insert to specifically target particles of specific mass and aerodynamic character.

[0013] This, the present invention is well suited to carry out the objects and attained the ends and advantages mentioned herein. While the preferred embodiments of the present invention have been described for the purposes of this disclosure, changes in the design and arrangement of features can be made by these skilled in the art, which changes are encompassed within the spirit of this invention as defined by the appended claims. 

What is claimed is:
 1. A vortex-funnel barrel devise for 25 mm cassettes that focuses and concentrates particulate, bioparticulate, and/or other agents in a definitive and distinct zone on a receiving filter, comprising: an insert that begins as a circular structure adaptable to current sampling cassettes available within the industry, that transitions into a flange, narrowing from top to bottom to produce rectangular dimensions at the generate a filter deposition trace on the receiving filter having dimensions of 5-15 mm in diameter; however other diameters are claimed relative to the types of particles desired to be collected.
 2. An insert adapted to be disposed in an air sampling cassette comprising: a combination of: a filter medium; and a hollow structure having a generally circular upstream opening, a downstream opening that is substantially rectangular and encompasses a smaller area than said upstream opening, and a substantially smooth wall disposed between said openings; wherein said downstream opening end of said structure is adapted to be juxtaposed said filter medium, wherein all air passing through said hollow structure passes through said filter medium, and wherein said structure has a downstream end, disposed downstream of said filter medium, that is adapted to communicate with vacuum generating apparatus that is adapted to cause ambient air to be sucked through said upstream opening and substantially all of said air passed through said downstream opening in said hollow structure.
 3. The insert as claimed in claim 2 wherein said filter medium is spaced from said downstream opening by up to about 2 mm.
 4. A cassette suitable for the sampling of ambient air to determine if it contains particulate matter comprising: an intake cap comprising at least one internal passageway adapted to communicate with an ambient environment; a cassette insert comprising at least one internal passageway adapted to communicate with said ambient environment through said internal passageway in said intake cap; and a filter assembly longitudinally proximate to a downstream end of said cassette passageway and in operative relationship with said cassette passageway such that substantially all air passing through said cassette passageway passes through said filter; wherein said cassette passageway comprises a circular cross section entry end opening proximate to said intake cap and a rectangular cross section exit end, of smaller area than said circular entry end, and opening proximate to said filter assembly.
 5. The cassette as claimed in claim 4 wherein said filter assembly is in intimate contact with said filter medium.
 6. The cassette as claimed in claim 5 wherein said internal passageways in said intake cap, said cassette insert and said exit means all have common axes.
 8. The cassette as claimed in claim 4 further comprising tubing attached to said intake cap, means to collect ambient air through said tubing, and vacuum generating means operatively associated with said filter and said insert and adapted to draw ambient air through said internal passageways. 